In this study patients with rheumatoid arthritis unresponsive or intolerant to gold therapy will be randomized in a double-blind trial to receive either azathioprine or d-penicillamine. The trial will compare the efficacy and toxicity of these during a 24 week trial and an extended follow-up observation period. The Arthritis and Rheumatism Branch is one of eleven clinics carrying out this protocol under the direction of the Center for Cooperative Studies in the Rheumatic Diseases.